Commonwealth Fusion Systems (CFS) is developing SPARC, a compact, high-field tokamak designed to demonstrate net energy gain from fusion. The device is engineered to produce more thermal power from fusion reactions than the electrical power required to operate its superconducting magnets and auxiliary systems. This milestone, targeted for 2027, would represent a critical step towards commercial fusion power generation, validating the company's high-field magnet technology and compact tokamak design.

SPARC's design leverages high-temperature superconducting (HTS) magnets, specifically REBCO (rare-earth barium copper oxide) tapes, to generate magnetic fields exceeding 12 tesla. These powerful fields enable a compact device geometry while confining a hot deuterium-tritium plasma at densities and temperatures sufficient for significant fusion power output. The machine is projected to achieve a Q_plasma greater than 10, meaning it will produce at least ten times the fusion power generated by the heating systems.

SPARC's design leverages high-temperature superconducting (HTS) magnets, specifically REBCO (rare-earth barium copper oxide) tapes, to generate magnetic fields exceeding 12 tesla.

Previous fusion experiments have achieved scientific breakeven (Q_plasma = 1) or approached it, but SPARC's objective is to surpass this by a substantial margin and achieve net energy gain in a commercially relevant context. The National Ignition Facility (NIF) achieved ignition (Q_plasma > 1) in inertial confinement fusion experiments, but SPARC's approach is magnetic confinement. The successful operation of SPARC would validate the physics and engineering principles underpinning CFS's commercialization strategy, paving the way for larger-scale power plant designs.

The project's success hinges on the performance of the HTS magnets, which are crucial for achieving the high magnetic field strengths required for efficient plasma confinement in a compact volume. CFS has already demonstrated the capability of these magnets in prototype tests, including the successful energization of a full-scale toroidal field coil to 12.7 tesla. This technological advancement is a key differentiator for CFS's approach to fusion energy.

SPARC's projected performance includes achieving a fusion power output of approximately 50 MW thermal, while requiring less than 5 MW of electrical power for magnet operation. This net energy gain, if realized, will provide crucial data for the design and economic viability of ARC, CFS's planned pilot power plant. The development of SPARC is a central pillar in the broader effort to accelerate the deployment of fusion energy as a clean and abundant power source.